/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package net.butfly.albacore.utils.collections;

import java.util.Map;

/**
 * Abstract Pair class to assist with creating correct
 * {@link java.util.Map.Entry Map.Entry} implementations.
 * 
 * @since Commons Collections 3.0
 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr
 *          2008) $
 * 
 * @author James Strachan
 * @author Michael A. Smith
 * @author Neil O'Toole
 * @author Stephen Colebourne
 */
public abstract class AbstractMapEntry extends AbstractKeyValue implements Map.Entry<String, Object> {

	/**
	 * Constructs a new entry with the given key and given value.
	 * 
	 * @param key
	 *            the key for the entry, may be null
	 * @param value
	 *            the value for the entry, may be null
	 */
	protected AbstractMapEntry(String key, Object value) {
		super(key, value);
	}

	// Map.Entry interface
	// -------------------------------------------------------------------------
	/**
	 * Sets the value stored in this <code>Map.Entry</code>.
	 * <p>
	 * This <code>Map.Entry</code> is not connected to a Map, so only the local
	 * data is changed.
	 * 
	 * @param value
	 *            the new value
	 * @return the previous value
	 */
	public Object setValue(Object value) {
		Object answer = this.value;
		this.value = value;
		return answer;
	}

	/**
	 * Compares this <code>Map.Entry</code> with another <code>Map.Entry</code>.
	 * <p>
	 * Implemented per API documentation of
	 * {@link java.util.Map.Entry#equals(Object)}
	 * 
	 * @param obj
	 *            the object to compare to
	 * @return true if equal key and value
	 */
	public boolean equals(Object obj) {
		if (obj == this) {
			return true;
		}
		if (obj instanceof Map.Entry == false) {
			return false;
		}
		Map.Entry<?, ?> other = (Map.Entry<?, ?>) obj;
		return (getKey() == null ? other.getKey() == null : getKey().equals(other.getKey()))
				&& (getValue() == null ? other.getValue() == null : getValue().equals(other.getValue()));
	}

	/**
	 * Gets a hashCode compatible with the equals method.
	 * <p>
	 * Implemented per API documentation of
	 * {@link java.util.Map.Entry#hashCode()}
	 * 
	 * @return a suitable hash code
	 */
	public int hashCode() {
		return (getKey() == null ? 0 : getKey().hashCode()) ^ (getValue() == null ? 0 : getValue().hashCode());
	}

}
